6. TROUBLESHOOTING
Page 175
© 2009 DH Instruments, a Fluke Company
SYMPTOM
PROBABLE CAUSE
SOLUTION
Pump drive pressure supply not connected,
incorrectly connected or not adequate.
Correct pressure supply. Observe pump
drive air pressure. 2.3.5, 3.5.7.3
Cannot get to maximum
pressure… pump stops pumping
Pump high pressure seals failing as
evidenced by liquid output or mist from the
pmp muffler.
Replace pump. 5.10.2
PG7302 piston drop rate is
unusually high when used with
PPCH.
Leak in PPCH.
Identify and correct leak. 5.11, 5.11.2
Pressurized fluid dripping from
PPCH enclosure.
PPCH internal leak to outside.
Open cabinet and look for visible leaks.
Tighten fittings if necessary. If liquid is
coming from pump muffler, replace pump.
5.9, 5.10.2
Poor pressure control characterized
by control interrupting near the
target pressure.
Control mode is set to static mode rather
than dynamic mode.
Set control mode to dynamic. 3.2.2,
3.4.6.2
Poor pressure control characterized
by pressure never stopping.
Control mode is set to monotonic or ramp
mode rather than dynamic or static mode.
Set control mode to dynamic or static.
3.2.2, 3.4.6.2
[ENT]
from main run screen doesn’t
result in a target pressure entry
screen.
Control mode is set to ramp mode rather
than dynamic, static or monotonic.
Set control mode to desired mode. 3.2.2,
3.4.6.2
There is a restriction in the test connection
between the PPCH and the test or the
PPCH, the RPM4 and the test.
Remove the restriction to allow free flow
between the PPCH, the RPM4 (if present)
and the test. 2.3.9
Thermal pressure control (TPC) module
needs to be reconfigured.
Reconfigure TPC module after all other
possible control issues are considered. 5.7
Poor pressure control characterized
by excessive overshooting/
undershooting and/or “hunting”
around target in dynamic control
mode.
Test volume has recently been changed
significantly.
Set pressure points and allow PPCH to
adapt to the new volume or run the TPCU
configuration. 5.14.2.15
Poor pressure control characterized
by overshooting target.
The volume connected to the
TEST
port is
too small.
Add volume to the system connected to the
TEST
port. 1.2.3
A filter in the PPCH or an accessory is dirty
and causing a restriction.
Replace the filter element.
Test volume is too large. Severe restriction
in a test line.
Reduce test volume if slew rate is
unacceptable. Remove restrictions in
line connected to
TEST
port.
Poor pressure control characterized
by very slow slew rate.
Pressure is below 1 MPa (150 psi) and
PPCH uses a special control algorithm to
avoid over pressuring poorly purged systems
Operation is normal. Wait for pressure to
change.
Excessive leak present in system.
Correct internal or external leak or increase
hold limit. 3.3.9, 3.4.6.1
Poor pressure control.
Excessive gas in PPCH and/or test system.
Purge system. 3.3.8.2
Inlet and/or outlet control valve not closing
fully.
Run valve opening point configuration.
5.8
Inlet and/or outlet control valve leaking.
Perform leak checking routines, replace
leaking valve. 5.11, 5.11.2
Poor pressure control characterized
by oscillating pressure.
System vent valve, Lo Q-RPT vent valve or
Lo Q-RPT shutoff valve leaking.
Perform leak checking routines, replace
leaking valve. 5.11, 5.11.2
Poor pressure control after recently
changing to standard dynamic
control mode.
Thermal pressure control unit (TPCU) is
initializing and causes pressure to change as
its temperature stabilizes.
Be sure PPCH is vented when changing
to or from standard dynamic control
mode and wait at least five minutes after
the mode change before setting a new
pressure target.
Disagreement between two Q-RPTs
in system appears excessive.
Difference is actually within tolerance and is
acceptable. Note the Internal, Hi transducer
may be a utility sensor which has a much
wider tolerance than a Q-RPT.
Compare differences observed to
tolerances of Q-RPT and/or utility sensor
measurements. 1.2.2.1, 1.2.2.2
Apparent inaccurate pressure
control/measure and little or no
response from Q-RPT or utility
sensor.
Reference transducer destroyed by
overpressure.
Contact
DHI
Authorized Service Provider.
Table 31
